In Halo: Reach I use Sprint for 90% of the times. I just need to get to places faster that why I pick Sprint lot. Only time I will change if there is a small map because you don't need to rush to much if you are in a small map. Then I will use others, but I will go back to Sprint. In a big team battle I will not use Sprint all the time because I want to use one that can help the team out. In Halo 4 I will start using other ones because I want to see the skills that I can use for the Map or Mode. It will make it more fun!